A method for the low stress forming of ultra-thin steel papers suitable for dry environments
Patent Information
- Application Number
- CN202611195872.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-07
- Publication Date
- 2026-10-16
AI Technical Summary
[0006]本申请提供一种适用于干燥环境的超薄钢纸低应力成型制备方法，旨在解决现有技术在干燥环境下制备超薄钢纸时存在的成型应力大、翘曲开裂严重以及尺寸稳定性差问题
[0017] This application gradually compensates for the loss of moisture in the base paper and stabilizes the moisture content. It utilizes high-concentration cross-linking and humidity buffering to control the fiber dehydration and shrinkage rate, and promotes the full relaxation of residual stress in the final stage, so that the internal stress of the finished product is reduced to below 0.8MPa and the warpage is controlled to below 0.2mm/m, thus ensuring the high dimensional stability of ultra-thin steel paper in a dry environment.
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Abstract
Description
Technical Field
[0001] This application relates to the field of steel paper production technology, specifically a method for preparing ultra-thin steel paper using low-stress molding suitable for dry environments. Background Technology
[0002] After being permeated, swollen and cross-linked gelled by zinc chloride solution, steel paper base paper (sulfurized fiber base paper) can be made into ultra-thin steel paper. With its excellent mechanical strength and electrical insulation properties, it has become a key substrate for high-end precision electrical insulation, new energy control components and aviation supporting insulation parts.
[0003] In typical arid regions of my country, such as Xinjiang and Northwest China, the air humidity is extremely low, the temperature difference between day and night is large, and there is little rainfall throughout the year. The relative humidity in conventional storage and production environments is often below 35% year-round. Under these conditions, steel-paper base paper is extremely prone to rapid moisture loss, leading to brittle fiber structure. Existing steel-paper production processes typically employ a fixed humidity control method within a single humidity range to treat the base paper, using a medium-to-low concentration of zinc chloride solution in conjunction with prolonged impregnation to prevent paper collapse, and finally completing the shaping process through high-temperature rapid drying.
[0004] However, there is a significant difference in moisture content between the surface and core layers of the base paper. During the subsequent impregnation process, the fibers experience internal stress concentration due to inconsistent swelling rates. When using low-to-medium concentration zinc chloride solution with prolonged impregnation, it is difficult to accurately control the depth of gelation, resulting in insufficient fiber cross-linking density. During the subsequent high-temperature drying and dehydration process, the excessively rapid removal rate of moisture prevents the effective release of internal stress as moisture migrates, easily leading to severe warping and deformation of the finished steel-paper product, excessively high thermal shrinkage rate, and dimensional drift, seriously affecting the yield and quality of the finished steel-paper product.
[0005] Therefore, there is an urgent need for a low-stress molding method for ultrathin steel paper that can adapt to dry climates and achieve high-concentration, short-term, precise cross-linking, in order to solve the above problems. Summary of the Invention
[0006] This application provides a low-stress molding preparation method for ultra-thin steel paper suitable for dry environments, aiming to solve the problems of high molding stress, severe warping and cracking, and poor dimensional stability in the preparation of ultra-thin steel paper in dry environments in the prior art.
[0007] To achieve the above objectives, this application provides the following technical solution: a method for preparing ultrathin steel paper under low stress in a dry environment, the method comprising the following steps: Pretreatment: The steel paper base paper is placed in a closed humidity control chamber, and a multi-stage gradient dynamic humidity adjustment process is adopted to gradually increase the relative humidity of the environment to compensate for the moisture loss of the base paper and stabilize the moisture content of the base paper. Gelation: A high-concentration zinc chloride solution was prepared and a nonionic surfactant was added. At a set impregnation temperature, the high-concentration zinc chloride solution was used to perform short-term cross-linking on the pretreated base paper with ultrasonic assistance. Slow drying and setting: The gelled steel paper is fed into a continuous wet heat setting machine and dried in multiple stages with gradient temperature increase under the condition of maintaining constant relative humidity. Stress relief: Place the shaped steel paper in a constant temperature and humidity environment to release stress; Post-processing: The steel paper that has reached the stress relief standard is taken out and subjected to surface cleaning and desalination to remove residual zinc chloride and additives. After final drying, it is slit and rolled to obtain the ultra-thin steel paper product.
[0008] Preferably, the sealed humidity control chamber adopts a closed-loop humidity control system, which includes a temperature sensor with an accuracy of ±0.5℃ and a humidity sensor with an accuracy of ±1%RH.
[0009] Furthermore, the multi-segment gradient dynamic humidity control includes: The first stage is controlled at a temperature of 25±1℃ and a relative humidity of 48±2%RH, with a duration of 0–4h. The second stage is controlled at a temperature of 27±1℃ and a relative humidity of 53±2%RH, with a duration of 4–10h. The third stage controls the temperature at 26±1℃ and the relative humidity at 56±2%RH, with a duration of 10–18 hours.
[0010] Preferably, the high-concentration zinc chloride solution has a Baume degree of 67±2°Bé.
[0011] Furthermore, the amount of the nonionic surfactant added is 0.3%–0.5% of the high-concentration zinc chloride solution.
[0012] Furthermore, the frequency of the ultrasound is 20Hz and the power is 50W.
[0013] Furthermore, the immersion temperature is 40±2℃, and the immersion time is 30–50s.
[0014] Preferably, the constant ambient relative humidity is 40%–45%RH, and the multi-stage gradient temperature drying includes: The temperature of the first segment is 42±1℃, and the time is 15±2min; The second stage temperature was 50±1℃, and the time was 12±2min; The third segment had a temperature of 58±1℃ and a duration of 8±2min.
[0015] Preferably, the temperature at which the object is placed in a constant temperature and humidity environment is 30±2℃, the relative humidity is 50±5%RH, and the standing time is 28–32h.
[0016] Preferably, the final drying temperature is 45–55°C, and the desalination treatment specifically involves spraying or rinsing the surface of the steel paper with deionized water until the pH value of the steel paper surface is neutral.
[0017] This application gradually compensates for the loss of moisture in the base paper and stabilizes the moisture content. It utilizes high-concentration cross-linking and humidity buffering to control the fiber dehydration and shrinkage rate, and promotes the full relaxation of residual stress in the final stage, so that the internal stress of the finished product is reduced to below 0.8MPa and the warpage is controlled to below 0.2mm / m, thus ensuring the high dimensional stability of ultra-thin steel paper in a dry environment.
[0018] This application utilizes a high-concentration zinc chloride solution combined with 20kHz ultrasound to achieve precise shallow cross-linking of fibers within a short impregnation time of 30–50 seconds. The ultrasonic cavitation effect accelerates the penetration of concentrated solution and breaks through the limitations of traditional low-concentration long-time impregnation processes, avoiding excessive swelling and collapse of fibers. This results in ultra-thin steel paper with a longitudinal tensile strength of not less than 50MPa and an electrical breakdown strength of not less than 7kV / mm, effectively improving the material's density and comprehensive mechanical properties.
[0019] This application utilizes a constant humidity environment and multi-stage gradient heating to effectively control the moisture removal rate by maintaining the relative humidity of the environment. This prevents the capillary tension caused by excessively rapid evaporation of surface moisture from pulling on the fiber structure, reducing the thermal shrinkage rate of the finished product to below 0.3%. This effectively meets the stringent processing requirements of high-end precision insulation components for material dimensional accuracy. Attached Figure Description
[0020] Figure 1 A flowchart illustrating the preparation method for low-stress molding of ultrathin steel paper suitable for dry environments. Detailed Implementation
[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Example
[0022] This embodiment provides a method for preparing ultrathin steel paper using low-stress molding suitable for dry environments, such as... Figure 1 As shown, the specific steps are as follows: S100, Pretreatment: The steel paper base paper (vulcanized fiber base paper) is placed in a closed humidity control chamber equipped with a closed-loop humidity control system, which includes a temperature sensor with an accuracy of ±0.5℃ and a humidity sensor with an accuracy of ±1%RH.
[0023] Among them, a three-stage gradient humidity conditioning process is adopted: First stage: Temperature controlled at 25℃, relative humidity at 48%RH, duration 4h, mainly used to replenish surface moisture; Second stage: Control the temperature at 27℃ and the relative humidity at 53%RH for 6 hours to promote the penetration of moisture into the fiber core layer; The third step: control the temperature at 26℃ and the relative humidity at 56%RH for 8 hours to stabilize the moisture content of the base paper.
[0024] S200, Gelation: Prepare a zinc chloride solution with a Baume degree of 67°Bé and add 0.3% by mass of a nonionic surfactant to reduce interfacial tension. Set the impregnation tank temperature to 40°C. Place the pretreated base paper into the solution and turn on an ultrasonic generator with a frequency of 20kHz and a power of 50W to assist in rapid penetration of the concentrated solution. The impregnation time is controlled at 40s.
[0025] S300, Slow Drying and Setting: The gelled steel paper is fed into a continuous wet heat setting machine. During the drying process, the relative humidity inside the machine is maintained at 40%RH to avoid stress concentration from rapid dehydration; The drying process is divided into three stages: The first stage, with a temperature of 42℃ and a time of 15 minutes, removes surface free water. The second stage, at a temperature of 50℃ for 12 minutes, removes free zinc chloride from the fiber gaps. The third stage, with a temperature of 58℃ and a duration of 8 minutes, completes the initial shaping.
[0026] S400, Stress Release: Place the shaped steel paper in an environment of 30℃ and 50%RH for 30 hours to release stress.
[0027] S500, Post-processing: Take out the stationary steel paper, spray it with deionized water until the surface pH value is neutral, and then dry it at 50℃. Cut and roll it to obtain an ultra-thin steel paper product with a thickness of 0.25mm. Example
[0028] This embodiment provides a method for preparing ultrathin steel paper using low-stress molding suitable for dry environments, such as... Figure 1 As shown, the specific steps are as follows: S100, Pretreatment: The steel paper base paper (vulcanized fiber base paper) is placed in a closed humidity control chamber equipped with a closed-loop humidity control system, which includes a temperature sensor with an accuracy of ±0.5℃ and a humidity sensor with an accuracy of ±1%RH.
[0029] Among them, a three-stage gradient humidity conditioning process is adopted: First stage: Temperature controlled at 24℃, relative humidity at 46%RH, duration 4h, mainly used to replenish surface moisture; Second stage: Control the temperature at 26℃ and the relative humidity at 51%RH for 6 hours to promote the penetration of moisture into the fiber core layer; The third step: control the temperature at 25℃ and the relative humidity at 54%RH for 8 hours to stabilize the moisture content of the base paper.
[0030] S200, Gelation: Prepare a zinc chloride solution with a Baume degree of 69°Bé and add 0.5% by mass of a nonionic surfactant to reduce interfacial tension. Set the impregnation tank temperature to 40°C. Place the pretreated base paper into the solution and turn on an ultrasonic generator with a frequency of 20kHz and a power of 50W to assist in rapid penetration of the concentrated solution. The impregnation time is controlled at 30s.
[0031] S300, Slow Drying and Setting: The gelled steel paper is fed into a continuous wet heat setting machine. During the drying process, the relative humidity inside the machine is maintained at 45%RH to avoid stress concentration from rapid dehydration; The drying process is divided into three stages: The first stage, with a temperature of 43℃ and a time of 13 minutes, removes surface free water. The second stage, with a temperature of 51℃ and a time of 10 minutes, removes free zinc chloride from the fiber gaps. The third stage, with a temperature of 59℃ and a duration of 6 minutes, completes the initial shaping.
[0032] S400, Stress Release: Place the shaped steel paper in an environment of 30℃ and 50%RH for 32 hours to release stress.
[0033] S500, Post-processing: Take out the stationary steel paper, spray it with deionized water until the surface pH value is neutral, and then dry it at 50℃. Cut and roll it to obtain an ultra-thin steel paper product with a thickness of 0.30mm. Example
[0034] This embodiment provides a method for preparing ultrathin steel paper using low-stress molding suitable for dry environments, such as... Figure 1 As shown, the specific steps are as follows: S100, Pretreatment: The steel paper base paper (vulcanized fiber base paper) is placed in a closed humidity control chamber equipped with a closed-loop humidity control system, which includes a temperature sensor with an accuracy of ±0.5℃ and a humidity sensor with an accuracy of ±1%RH.
[0035] Among them, a three-stage gradient humidity conditioning process is adopted: First stage: Temperature controlled at 26℃, relative humidity at 50%RH, duration 4h, mainly used to replenish surface moisture; Second stage: Control the temperature at 28℃ and the relative humidity at 55%RH for 6 hours to promote the penetration of moisture into the fiber core layer; The third step: control the temperature at 27℃ and the relative humidity at 58%RH for 8 hours to stabilize the moisture content of the base paper.
[0036] S200, Gelation: Prepare a zinc chloride solution with a Baume degree of 65°Bé and add 0.4% by mass of a nonionic surfactant to reduce interfacial tension. Set the impregnation tank temperature to 40°C. Place the pretreated base paper into the solution and turn on an ultrasonic generator with a frequency of 20kHz and a power of 50W to assist in rapid penetration of the concentrated solution. The impregnation time is controlled at 50s.
[0037] S300, Slow Drying and Setting: The gelled steel paper is fed into a continuous wet heat setting machine. During the drying process, the relative humidity inside the machine is maintained at 42%RH to avoid stress concentration from rapid dehydration; The drying process is divided into three stages: The first stage, with a temperature of 41℃ and a time of 17 minutes, removes surface free water. The second stage, at a temperature of 49℃ for 14 minutes, removes free zinc chloride from the fiber gaps. The third stage, with a temperature of 57℃ and a duration of 10 minutes, completes the initial shaping.
[0038] S400, Stress Release: Place the shaped steel paper in an environment of 30℃ and 50%RH for 28 hours to release stress.
[0039] S500, Post-processing: Take out the stationary steel paper, spray it with deionized water until the surface pH value is neutral, and then perform final drying at 50℃. Cut and roll it to obtain an ultra-thin steel paper product with a thickness of 0.40mm.
[0040] Comparative Example 1 This comparative example uses a conventional steel paper production process, which differs from Examples 1, 2, and 3 in that: Humidity conditioning: Place the steel paper base directly in a normal workshop environment with a relative humidity of 30% for 24 hours to equilibrate.
[0041] Gelation: Prepare a low-concentration zinc chloride solution with a Baume degree of 55°Bé, and impregnate the base paper at room temperature for 10 minutes.
[0042] Drying: The impregnated steel paper is directly sent into the drying oven and dried quickly at a high temperature of 80℃.
[0043] Post-treatment: After drying, allow to cool naturally, then perform a simple surface wash and dry.
[0044] The performance of the ultrathin steel paper products prepared in Examples 1-3 and Comparative Example 1 was tested.
[0045] The test items and methods are as follows: Moisture content: Tested according to GB / T 462-2008; Longitudinal tensile strength: tested according to GB / T 1040.3-2006; Electrical breakdown strength: tested according to GB / T 1408.1-2006; Heat shrinkage rate: determined according to relevant industry standards after heating at 105℃ for 1 hour; Warpage: Place the sample flat on a horizontal platform and measure the ratio of the maximum arch height to the length (mm / m). Internal stress: measured using a dedicated stress testing instrument.
[0046] The test results are shown in the table below: As shown in the table above, the steel paper prepared in Comparative Example 1 has extremely high internal residual stress, resulting in a warpage as high as 0.85 mm / m and a thermal shrinkage rate exceeding 0.6%, making it difficult to meet the processing requirements of precision insulating parts. In contrast, the steel paper prepared in Examples 1, 2, and 3, through a three-stage gradient humidity conditioning process and a three-stage slow drying and shaping process, can effectively control the warpage to within 0.2 mm / m and the thermal shrinkage rate to below 0.3%, meeting the processing requirements of precision insulating parts. Furthermore, through the synergistic effect of high-concentration zinc chloride and ultrasound, the steel paper fibers in the examples exhibit more dense and uniform cross-linking, with longitudinal tensile strength generally exceeding 50 MPa and breakdown strength exceeding 7 kV / mm, significantly higher than Comparative Example 1.
[0047] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and concept of this application, should be included within the scope of protection of this application.
Claims
1. A method for preparing ultrathin steel paper under low stress in a dry environment, characterized in that, Includes the following steps: Pretreatment: The steel paper base paper is placed in a closed humidity control chamber, and a multi-stage gradient dynamic humidity adjustment process is adopted to gradually increase the relative humidity of the environment to compensate for the moisture loss of the base paper and stabilize the moisture content of the base paper. Gelation: A high-concentration zinc chloride solution was prepared and a nonionic surfactant was added. At a set impregnation temperature, the high-concentration zinc chloride solution was used to perform short-term cross-linking on the pretreated base paper with ultrasonic assistance. Slow drying and setting: The gelled steel paper is fed into a continuous wet heat setting machine and dried in multiple stages with gradient temperature increase under the condition of maintaining constant relative humidity. Stress relief: Place the shaped steel paper in a constant temperature and humidity environment to release stress; Post-processing: The steel paper that has reached the stress relief standard is taken out and subjected to surface cleaning and desalination to remove residual zinc chloride and additives. After final drying, it is slit and rolled to obtain the ultra-thin steel paper product.
2. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 1, characterized in that, The sealed humidity control chamber adopts a closed-loop humidity control system, which includes a temperature sensor with an accuracy of ±0.5℃ and a humidity sensor with an accuracy of ±1%RH.
3. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 2, characterized in that, The multi-segment gradient dynamic humidity control includes: The first stage is controlled at a temperature of 25±1℃ and a relative humidity of 48±2%RH, with a duration of 0–4h. The second stage is controlled at a temperature of 27±1℃ and a relative humidity of 53±2%RH, with a duration of 4–10h. The third stage controls the temperature at 26±1℃ and the relative humidity at 56±2%RH, with a duration of 10–18 hours.
4. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 1, characterized in that, The high-concentration zinc chloride solution has a Baumé degree of 67 ± 2°Bé.
5. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 4, characterized in that, The amount of nonionic surfactant added is 0.3%–0.5% of the high-concentration zinc chloride solution.
6. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 4, characterized in that, The ultrasonic wave has a frequency of 20Hz and a power of 50W.
7. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 4, characterized in that, The immersion temperature is 40±2℃, and the immersion time is 30–50s.
8. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 1, characterized in that, The constant ambient relative humidity is 40%–45%RH, and the multi-stage gradient temperature drying includes: The temperature of the first segment is 42±1℃, and the time is 15±2min; The second stage temperature was 50±1℃, and the time was 12±2min; The third segment had a temperature of 58±1℃ and a duration of 8±2min.
9. The method for preparing ultrathin steel paper under low stress in a dry environment according to claim 1, characterized in that, The temperature for placing the object in a constant temperature and humidity environment is 30±2℃, the relative humidity is 50±5%RH, and the standing time is 28–32h.
10. The method for preparing ultrathin steel paper in a dry environment according to claim 1, characterized in that, The final drying temperature is 45–55°C, and the desalination treatment specifically involves spraying or immersing the steel paper surface with deionized water until the pH value of the steel paper surface is neutral.